#!/bin/sed -f
/../! b
# Reverse a line. Begin embedding the line between two newlines
s/^.*$/\n&\n/
# Move first character at the end. The regexp matches until
# there are zero or one characters between the markers
tx
:x
s/\(\n.\)\(.*\)\(.\n\)/\3\2\1/
tx
# Remove the newline markers
s/\n//g